Download nonulcerative keratitis

NONULCERATIVE KERATITIS
(TYPE OF INFLAMMATION OF THE CORNEA)
BASICS
OVERVIEW
 “Keratitis” is inflammation of the cornea; the “cornea” is the clear outer layer of the front of the eye
 “Nonulcerative keratitis” is any inflammation of the cornea that does not retain fluorescein stain; “fluorescein stain” is a dye
that is used to identify ulcers of the cornea—if the very top layer of the cornea has been disrupted (as with an ulcer), the dye
will enter the lower layers of the cornea and will cause a temporary stain that glows under an ultraviolet light; in nonulcerative
keratitis, the top layer of the cornea is not disrupted, so no dye enters the lower layers of the cornea
GENETICS
 No proven genetic basis in dogs or cats
 Long-term (chronic) superficial inflammation of the cornea (keratitis), also known as “pannus”—inherited susceptibility
considered in the German shepherd dog
SIGNALMENT/DESCRIPTION of ANIMAL
Species
 Dogs and cats
Breed Predilections
 Long-term (chronic) superficial inflammation of the cornea (keratitis), also known as “pannus”—may occur in any breed;
high likelihood in German shepherd dogs and Belgian Tervuren
 Inflammation characterized by the presence of pigment (melanin) that is deposited in the cornea (known as “pigmentary
keratitis”)—seen in short-nosed, flat-faced (known as “brachycephalic”) breeds of dogs with inflammation of the cornea due
to exposure to air and irritants (known as “exposure keratopathy”) from condition in which the eyelids do not close completely
(known as “lagophthalmos”) and tear-film deficiencies; prominent folds of skin around the nose; abnormal eyelashes that turn
inward, against the cornea (known as “trichiasis”); notably identified in pugs, Lhasa apsos, shih tzus, Pekingese
 Inflammation usually involving the area where the cornea (clear part of the eye) and the sclera (white part of the eye) come
together, characterized by the presence of nodules (condition known as “nodular granulomatous episcleritis”)—may occur in
any breed; likely in cocker spaniels, greyhounds, collies and Shetland sheepdogs
 “Dry eye” (known as “keratoconjunctivitis sicca” or “KCS”)—seen in short-nosed, flat-faced (brachycephalic) breeds;
notably cocker spaniels, English bulldogs, Lhasa apsos, shih tzus, pugs, West Highland white terriers, Pekingese, Cavalier
King Charles spaniels
 Condition in which part of the cornea tissue dies, leaving a pigmented lesion and fluid build-up (known as edema; condition
known as “corneal sequestration”)—most prevalent in Persians, Siamese, Burmese, and Himalayans
Mean Age and Range
 Long-term (chronic) superficial inflammation of the cornea (keratitis), also known as “pannus”—may occur at any age;
higher risk at 4 to 7 years of age
 Inflammation characterized by the presence of pigment (melanin) that is deposited in the cornea (pigmentary keratitis)—may
occur at any age
 Inflammation usually involving the area where the cornea (clear part of the eye) and the sclera (white part of the eye) come
together, characterized by the presence of nodules (nodular granulomatous episcleritis)—may occur at any age; in collies—
young to middle-aged (mean age, 3.8 years)
 “Dry eye” (keratoconjunctivitis sicca or KCS)— usually middle-aged or old
 Herpesvirus in cats—all ages
 Inflammation of the cornea, characterized by the presence of a type of white-blood cell, called an “eosinophil” (condition
known as “eosinophilic keratitis”) and condition in which part of the cornea tissue dies, leaving a pigmented lesion and fluid
build-up (known as edema; condition known as “corneal sequestration”) in cats—all ages, except newborns
SIGNS/OBSERVED CHANGES in the ANIMAL
 May cause variable discoloration of the cornea
 Variable eye discomfort
Dogs
 Long-term (chronic) superficial inflammation of the cornea (keratitis), also known as “pannus”—usually involves both eyes;
often symmetrical pinkish white lesions with variable pigmentation; usually seen on the outer and/or lower part of the cornea;
third eyelids may be affected and appear thickened or depigmented; white lipid (a group of compounds that contain fats or
oils) deposits may be present at adjacent corneal edge; may lead to blindness in advanced disease
 Inflammation characterized by the presence of pigment (melanin) that is deposited in the cornea (pigmentary keratitis)—
appears as focal to diffuse brown to black discoloration of the cornea; often associated with encroachment of blood vessels
into corneal tissue (known as “corneal vascularization”) or scarring
 Inflammation usually involving the area where the cornea (clear part of the eye) and the sclera (white part of the eye) come
together, characterized by the presence of nodules (nodular granulomatous episcleritis)—usually involves both eyes; raised
pink to tan lesions of the outer part of the cornea; may be slowly to rapidly progressive; white deposits and encroachment of
blood vessels into corneal tissue (corneal vascularization) may occur in adjacent corneal tissue; third eyelids may appear
thickened
 “Dry eye” (keratoconjunctivitis sicca or KCS)—variable findings; may involve one or both eyes; discharge from the eye(s)
may contain mucus and/or pus; redness of the moist tissues of the eye (known as “conjunctival hyperemia”); encroachment of
blood vessels into corneal tissue (corneal vascularization); pigmentation; and variable scarring
Cats
 Herpesvirus (nonulcerative; involves the thick, clear middle layer of the cornea [known as the “stroma”])—may involve one
or both eyes; often occurs with ulceration; fluid build-up in the cornea (known as “corneal edema”), infiltrates, encroachment
of blood vessels into corneal tissue (corneal vascularization), scarring; may threaten vision, if severe scarring
 Inflammation of the cornea, characterized by the presence of a type of white-blood cell, called an “eosinophil” (condition
known as “eosinophilic keratitis”)—usually involves only one eye; appears as raised white, pink, or gray corneal plaque with
roughened surface; may retain fluorescein stain at the edge of the lesion
 Condition in which part of the cornea tissue dies, leaving a pigmented lesion and fluid build-up (known as edema; condition
known as “corneal sequestration”)—usually involves only one eye, but can involve both eyes; appears as amber, brown, or
black oval to circular plaques near the center of the cornea; can vary in size and corneal depth; edges may appear raised
because of fluid build-up in the cornea (corneal edema); thickened tissue; encroachment of blood vessels into corneal tissue
(corneal vascularization) is variable; may retain fluorescein at edge of lesion
CAUSES
Dogs
 Long-term (chronic) superficial inflammation of the cornea (keratitis), also known as “pannus”—presumed to be immunemediated; altitude and solar radiation increase the likelihood and severity of the disease
 Inflammation characterized by the presence of pigment (melanin) that is deposited in the cornea (pigmentary keratitis)—
secondary to any long-term (chronic) corneal irritation; evaluate for primary underlying eye conditions; more frequently
associated with exposure corneal disease (exposure keratopathy) and “dry eye” (keratoconjunctivitis sicca or KCS)
 Inflammation usually involving the area where the cornea (clear part of the eye) and the sclera (white part of the eye) come
together, characterized by the presence of nodules (nodular granulomatous episcleritis)—presumed to be immune-mediated
 “Dry eye” (keratoconjunctivitis sicca or KCS)—usually caused by immune-mediated inflammation of the lacrimal gland that
produces tears (condition known as “dacryoadenitis”)
Cats
 Herpesvirus—believed to be immune-mediated reaction to herpesvirus antigen rather than an actual effect of the viral
infection
 Inflammation of the cornea, characterized by the presence of a type of white-blood cell, called an “eosinophil” (condition
known as “eosinophilic keratitis”)—unknown; some cats are infected with herpesvirus
 Condition in which part of the cornea tissue dies, leaving a pigmented lesion and fluid build-up (known as edema; condition
known as “corneal sequestration”)—unknown; likely due to long-term (chronic) corneal irritation; some cats have history of
previous trauma; suggested relationship with previous herpesvirus infection
RISK FACTORS
 Dogs—long-term (chronic) superficial inflammation of the cornea (keratitis), also known as “pannus”—more likely to occur
at high altitudes with intense sunlight
TREATMENT
HEALTH CARE
 Outpatient—generally sufficient
 Inpatient—cases that warrant surgery due to inadequate response to medical therapy
 Long-term (chronic) superficial inflammation of the cornea (keratitis), also known as “pannus”—radiation therapy (using βirradiation with a strontium-90 probe)
 Inflammation characterized by the presence of pigment (melanin) that is deposited in the cornea (pigmentary keratitis)—
radiation therapy (using β-irradiation) and freezing (known as “cryotherapy”)
SURGERY
Dogs
 Long-term (chronic) superficial inflammation of the cornea (keratitis), also known as “pannus”—surgical removal of the
surface of the cornea (known as “superficial keratectomy”) may be performed for severe disease; usually unnecessary; even if
surgery is performed, still requires indefinite medial treatment to prevent recurrence
 Inflammation characterized by the presence of pigment (melanin) that is deposited in the cornea (pigmentary keratitis)—
surgical removal of the surface of the cornea (superficial keratectomy) may be performed only after initial underlying cause is
corrected; surgery only in severe cases in which inflammation threaten vision
 Inflammation usually involving the area where the cornea (clear part of the eye) and the sclera (white part of the eye) come
together, characterized by the presence of nodules (nodular granulomatous episcleritis)—surgical removal of the surface of the
cornea (superficial keratectomy) is diagnostic; usually unnecessary; only temporarily resolves clinical signs; medical treatment
still is required
 “Dry eye” (keratoconjunctivitis sicca or KCS)—surgically move the duct from the parotid salivary gland to the eye
(procedure known as a “parotid duct transposition”), the saliva then acts as “tears” in the eye, or permanent partial closure of
the eyelids (surgical procedure known as a “tarsorrhaphy”) may be indicated
Cats
 Inflammation of the cornea, characterized by the presence of a type of white-blood cell, called an “eosinophil” (condition
known as “eosinophilic keratitis”)—surgical removal of the surface of the cornea (superficial keratectomy) is diagnostic;
usually unnecessary; only temporarily resolves clinical signs; medical treatment is preferred
 Condition in which part of the cornea tissue dies, leaving a pigmented lesion and fluid build-up (known as edema; condition
known as “corneal sequestration”)—surgical removal of the surface of the cornea (superficial keratectomy) may be curative;
recurrence is possible; eye discomfort is primary indication for surgery
MEDICATIONS
Medications presented in this section are intended to provide general information about possible treatment. The treatment for a
particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all
inclusive.
Dogs
 Long-term (chronic) superficial inflammation of the cornea (keratitis), also known as “pannus”—steroids (1% prednisolone
or 0.1% dexamethasone) applied to the eye directly (known as “topical treatment”); 1% or 2% cyclosporine in oil or 0.2%
ointment to decrease the immune response, applied to the eye directly (topical treatment); either of these medications can be
used alone or in combination for more severe cases; steroid (triamcinolone) injection under the moist tissues of the eye
(known as “subconjunctival injection”) can be used in addition to topical therapy in severe cases
 Inflammation characterized by the presence of pigment (melanin) that is deposited in the cornea (pigmentary keratitis)—
medications applied to the eye directly (topical treatment) to treat underlying cause; topical steroids, if primary cause is
inflammatory; lubricants or cyclosporine, if primary condition is “dry eye” (keratoconjunctivitis sicca or KCS); cyclosporine
may be beneficial to reduce pigmentation
 Inflammation usually involving the area where the cornea (clear part of the eye) and the sclera (white part of the eye) come
together, characterized by the presence of nodules (nodular granulomatous episcleritis)—steroids and/or cyclosporine applied
to the eye directly (topical treatment); systemic azathioprine (a chemotherapeutic agent used to decrease the immune response)
may be effective when used alone or in combination with topical medications
 “Dry eye” (keratoconjunctivitis sicca or KCS)—topical 1% or 2% cyclosporine in oil or 0.2% ointment
Cats
 Herpesvirus—topical (applied to the eye directly) antiviral agents (such as trifluridine—Viroptic®); for disease of the thick,
clear middle layer of the cornea (the stroma); topical steroids can be used at the same time as antiviral agents, but with
caution; oral lysine may be of benefit; oral antiviral agents should be used with extreme caution because of bone-marrow
suppression, leading to low red-blood cell and low white-blood cell counts, that could proceed to death
 Inflammation of the cornea, characterized by the presence of a type of white-blood cell, called an “eosinophil” (condition
known as “eosinophilic keratitis”)—steroids (1/8 to 1% prednisolone or 0.1% dexamethasone) applied to the eye directly
(topical treatment) usually causes remission; steroids should be used with caution and the patient monitored for ulceration or
worsening of clinical signs; topical antiviral medications can be used in combination with steroids, if herpesvirus infection is
suspected; for severe cases that do not respond to medical treatment, megestrol acetate (Ovaban®) can be considered;
megestrol acetate has side effects that you should discuss with your pet’s veterinarian
 Condition in which part of the cornea tissue dies, leaving a pigmented lesion and fluid build-up (known as edema; condition
known as “corneal sequestration”)—triple antibiotic applied to the eye directly (topical treatment) as directed by your pet’s
veterinarian for associated corneal ulceration; artificial tear lubrication may be beneficial for relieving discomfort; topical
antiviral medications can be used, if herpesvirus infection is suspected; topical 1% atropine ointment may be used to treat pain
associated with coexistent inflammation of the front part of the eye, including the iris (known as “anterior uveitis”), if clinical
signs suggestive of uveitis are present
FOLLOW-UP CARE
PATIENT MONITORING
 Periodic eye examinations to evaluate effectiveness of treatment; examine at 1 to 2 week intervals, gradually lengthening the
interval with remission or resolution of clinical signs
POSSIBLE COMPLICATIONS
 Continued eye discomfort
 Visual defects
 Blindness in severe cases
EXPECTED COURSE AND PROGNOSIS
 Depend on disease and underlying cause
KEY POINTS
Dogs
 All patients require lifelong treatment
 Nonulcerative keratitis is controlled rather than cured
 Surgery may be needed for treatment; some animals will continue to need medical treatment following surgery
Cats
 Herpesvirus—eye discomfort and inflammation of the cornea (keratitis) often recur
 Inflammation of the cornea, characterized by the presence of a type of white-blood cell, called an “eosinophil” (condition
known as “eosinophilic keratitis”)—disease controlled rather than cured
 Condition in which part of the cornea tissue dies, leaving a pigmented lesion and fluid build-up (known as edema; condition
known as “corneal sequestration”)—the pigmented lesion (known as a “sequestrum”) may slough spontaneously; may require
months to years of treatment and clinical course may be prolonged without surgery; removal of sequestrum by surgical
removal of the surface of the cornea (superficial keratectomy) may be incomplete and it may recur postoperatively